1. Field of the Invention
The present invention relates to a ball valve with sealing means for the closure part.
2. Description of the Related Art
In known valves, the spherical closure part consists of a single component with a cylindrical continuation for bearing the closure part and with an actuating handle.
In known valves, the sealing means usually consist of a coating of rubber or a similar material which sheathes the entire spherical body of the closure part and the bearing part of cylindrical construction, the sheathing which usually consists of rubber forming an annular sealing means. The sealing ring cooperates with a receiving seat which is recessed into a neck-like continuation of the valve body. The neck-like continuation of the valve body is constructed to be open towards the outside and to be coaxial with the receiving seat for the closure part and receives adjusting devices which can be removed from the shut-off member.
The known valves, which are fitted with a coated closure part, allow omission of the known seals which are located opposite one another and surround the shut-off means made of metal and with a ground surface. Furthermore, it is possible for the longitudinal dimension of the valve body to be reduced. However, in practice it has been proven with valves of this type that the valves fitted with a coated, spherical closure part have several disadvantages.
The integral component, consisting of the closure part, the cylindrical bearing part and the actuating handle, can be produced in one injection-molding operation; subsequently, the component is to be sheathed with the coating forming the seal by a further production operation. High processing accuracy and surface quality are required for the outer surface which is used for sealing. This requires the use of complex production processes, which has a disadvantageous effect on the production costs. Moreover, great expenditure is required for expensive sealing material. The production is subject to a low output rate and the production expenditure occurring is substantial.
Slight inaccuracies in the dimensions and the surface finish can adversely affect the sealing effect or lead to stiffness during opening and closing of the valve.